Objective To observe the safety and efficacy of posterior vitreous detachment (PVD) induced by combined intravetreal injection of lysineplasminogen and reteplase in rabbits.Methods Fifteen healthy New Zealand rabbits were divided into three groups with five rabbits in each. Take the right eyes as experimental eyes，while the left eyes as the control. The experimental eyes of three groups received combined intravetreal injection of 1250 mu;g/ml lysineplasminogen at 0.1 ml dose and 104U，3times;104U，105U reteplase at 0.05 ml dose recpectively, while the control eyes were injected intravetreally with 0.15 ml balanced salt solution. The conjunctiva, anterior chamber, lens, vitreous body, and retina were examined by slit lamp microscope and +120D preset lens. The retinal function was examined by electroretinogram (ERG).Results All the experimental eyes had PVD. The results of optical microscope showed that no change in retinal structure was found in the control group and 104 U reteplase group, clear retinal hierarchical but decreased ganglion cells and kernel layer cells were found in 3times;104 U reteplase group, only retinal pigment epithelium layer but no normal retinal structure was observed in 105U reteplase group. The results of ERG showed that compared the maximum mixed reaction of a and b wave amplitude in control group and reteplase group respectively, the difference was not statistically siginificant between 104U reteplase group and control group(a wave：t=0.881，-1.773，0.809；b-wave：t=-0.223，-0.441，1.400；P＞0.05),the differences were statistically siginificant between 3times;104 U(a wave：t=-3.20，b-wave：t=-4.182，-4.103),105 U reteplase group(a wave：t=-0.737，b wave：t=-15.150，6.597)and control group(P＜0.05). The control eyes didnprime;t had PVD.Conclusion Combined intravetreal injection of lysine-plasminogen and reteplase can induce complete PVD, and no damage to the retinal structure in rabbits.
Objective To investigate the dosage, efficacy and safety of intrav itreal injection of plasmin in producing posterior vitreous detachment (PVD), an d the possible role of plasmin in degrading adhesion glycoproteins of inner limiting membrane (ILM).Methods Twenty eyes of young human cadavers within 24 hours after death were divided into 4 groups that received 0.1 ml balanced salt solution (group 1) as control, 1 (group 2), 2 (group 3), or 3 (group 4) U of human plasmin. Optical and transmission electron microcopies were performed to examine the ultrastructure of the vitreoretinal interface. Electron-immunocytochemical techniques were carried out on ILM to estimate the content of fibronectin (FN) and laminin (LN). Flow cytometry was used for cell viability analysis of variance (ANOVA) and Tukey-test was employed for statistical analysis. Results Microscopy demonstrated that plasmin especially in group 4 cleaved the attachment of the vitreous collagen fibrils to the ILM with no evident damage to the inner retina. The content of LN, FN in ILM decreased with injection of plasmin (group 3 and 4 had statistical significance from control group for FN,P＜0.05; for LN in group 4, P＜0.05). Retinal cell viability was similar for plasmin-treated and control eyes. Conclusion Human plasmin disrupts the attachment of posterior hyaloid to the ILM with no morphologic changes of the inner retina. PVD is induced mostly with injection of 3 U plasmin. (Chin J Ocul Fundus Dis，2003，19：42-45)